Deeper Than Just Blood
by Diluted Thoughts
Summary: These feelings she harbored for him ran deeper than just blood. Light/Sayu. Incest.


_Obvious out of character-ness. Rated for. Well. Themes and the such._

* * *

"Sayonara, Sayu-chan! See you tomorrow!"

"Hai." Sayu waved a hand to her friend before opening the door and entering her home. The smile she had so forcefully plastered onto her face immediately dropped, and she leaned against the back of the door for support, putting a cold hand to her forehead.

Home.

Sayu began her ascent of the stairs slowly, almost reluctantly. She was fervently hoping that no one else was home, not even her mother. She just couldn't deal with trying to put on a brave face and talking to anyone right now, especially not—

Sayu abruptly found herself crashing into someone. The side of her face touched the soft plush of a bathrobe, and she smelled the warm, clean scent of someone who had just taken a shower.

"Sayu?

—_him_.

She blinked as she took in what had happened. "G-Gomen, onii-chan! I didn't mean to…"

She trailed off, biting back a gasp as her face prickled with a scarlet brush. Her brother, Light, stood in front of her wearing only a dark blue bathrobe. It had been haphazardly tied at the front, making the neckline slope dangerously low to reveal an incredibly well-toned chest. A towel was held to his auburn hair, which was slightly mussed and dripping wet.

Sayu suddenly became conscious of the fact that she had been staring at her brother longer than she should have and quickly glanced away, silently cursing herself.

Light laughed a low, slightly husky laugh, seeming genuinely amused. "I probably look like a mess, don't I?" he asked carelessly. She counted her blessings, glad he had mistaken her staring as shock at his messy appearance rather than shock at…

…well…

…how _hot_ he looked.

"You're home early today, onii-chan," she said in a hasty attempt to change the subject. Sayu looked at her brother as casually as possible, hoping that her face still wasn't flushed.

Light nodded as be began to dry off his hair with the towel. "Midterm week started today. We get to leave right after completing them."

"Oh…" She looked for something exciting to say before lamely finishing with "…that's good."

He laughed again, and this time she knew he was laughing at her. Sayu bit her lip and looked away, hating herself for fumbling with her words so much and acting so love-struck. At this rate, Light would easily be able to figure out that she…

"Sayu." She looked up at her brother when she felt his hand come down to rest on her shoulder. His warm touch caused a little shiver to run down her spine.

"You don't have to be so self-conscious around me." He grinned at her, the gleam in his light brown eyes matching the gleam of his perfect white teeth. "After all…" Light brushed past her, heading towards his room.

"…I _am _your brother."

Sayu closed her eyes and sighed softly.

And that was the problem.

* * *

After grudgingly eating a piece of fruit and onigiri at her mother's insistence, Sayu trudged back into her room. She made a point of shutting and locking the door as loudly as she could before finally collapsing onto her bed.

She shut her eyes…

_Light. _

…only to open them a second later in exasperation.

This always happened; she would try to cease her thoughts of him, but would merely end up failing in her efforts more quickly than the times before. And that would leave her frustrated and angry at herself. And then she would curse herself for having developed such an illicit crush on her brother in the first place.

Sayu sat up in her bed, idly fiddling with the hem of her blouse to give herself something to do.

Why exactly _had_ she become so infatuated with Light?

She'd gone over it in her head more times than she could count, yet still she came out with no clear answer.

It had just…happened.

She remembered what her friends said any time they came over. "You're brother is so unbelievably hot!" was their most predictable remark whilst they giggled and gawked at him like he was some sort of object. Of course she would only smile and nod in response, already well aware of the fact that her brother was handsome. Why else would so many girls call him over the weekend?

But then once her friend had chosen to say, "You're lucky to have a brother as hot as him."

And since the comment had casually been inserted into their everyday conversation, Sayu hadn't thought of it too much…well, until later, that is. Upon arriving home and seeing her brother leaning against their kitchen counter with a book in hand, reading, it had suddenly occurred to that her that he wasn't just handsome—he was breathtakingly good-looking. And intelligent. And confident. And just so…

Perfect.

What had been her first reaction to such thoughts? She had chastised herself, obviously. _Light's your brother, Sayu,_ she had told herself. _He's __related__ to you and you guys have the __same__ parents. Having a crush on your older brother isn't normal! It's immoral and __**wrong**__!_

So she had managed to brush aside that little flutter her heart gave every time he looked or talked to her as best she could by relating it all to the fact that she was maturing.

But the longer she denied her attraction the harder it became. Little things about him began affecting her. Like the way his voice made even the most ordinary of things sound extraordinary…or the way his bangs always fell over his eyes no matter how many times he pushed them away with his nimble fingers.

Getting help with homework had slowly become a routine. She found herself going in to ask him for help with the smallest things just to spend time with him. Prolonging their sessions together was another thing she had become quite good at doing, and she would intentionally miscalculate or answer a problem incorrectly so that he could explain the question to her again.

But even that had become unbearable because she knew it was so wrong. The way he reached and leaned over her to explain the question, the way his warm breath tickled her ear and caused her neck to prickle…it had all been too much for her. She had found maintaining her composure, let alone focusing, become increasingly difficult with his musky scent overwhelming her senses.

So she had abruptly stopped asking for help all together. In fact, she had begun avoiding him as much as possible, spending her weekends cooped up in her room and choosing to eat her dinner alone. The thought of accidentally doing something that she would surely regret later on proved to be enough to keep her away.

At least for now.

Saying that she was pleased with her decision was a lie. It tore her apart inside every time she glimpsed him in his room studying, or heard him discussing the progress of the Kira case with their father. And when she did bother going outside and hanging out with her friends, she couldn't engage in conversation with them as she used to. Even a new movie by Ryuuga Hideki hadn't been able to spur her out of her detachment. All the other boys just seemed to pale in comparison now.

She secretly envied Misa for being able to date her brother so openly and freely. Deep down inside she hated it when Misa came over for a date. The way she giggled and clung to him and said, "Oh, _Light_!" like some lovesick puppy was beyond infuriating. It took everything she had just to keep from throttling her and keep up her charade of admiring and complimenting Misa for being the perfect girl for her brother.

Sayu pulled her legs up to her chest and locked her arms tightly around her knees, burying her face in her arms.

Why, _why_ did she have to be related to Light?

* * *

A sigh left Sayu's lips as she smoothed the creases on her violet pajamas before hitting off the light switch and leaving the bathroom. A warm shower was just what she had needed to relax her tensed nerves. She was glad there was a school holiday that awarded them a day off before starting the weekend because there was nothing more she wanted than to sleep. It was the only time she was able to find some peace of mind and escape from her thoughts.

Sayu stifled a yawn as she reached her room, contemplating the idea of going to sleep then to avoid having dinner with her family. She opened the door to her room and stepped inside, shutting it before realizing that she wasn't alone.

Light was stretched out comfortably on her bed, diligently perusing her Algebra course book with a hand against his chin. He glanced up, giving her a ghost of a smile as she stared at him in shock.

"I hope I didn't startle you, Sayu."

Well that was the understatement of the year. Couldn't he see the look on her face?

"No," she said quickly. Perhaps too quickly. "It's okay, onii-chan. Really."

Sayu quickly walked over to her dressing table, feeling Light's eyes on her back as she took a seat on the stool and began combing the tangles out of her hair. The feeling of him watching her was unnerving to say the very least, and she tried her best to act as natural as she could.

After a few more minutes of staring in silence, he finally glanced away and set down her Algebra book. Sayu looked at his reflection in her mirror, watching as he swung his legs over the bed and got to his feet. He began straightening the wrinkles in his scarlet dress shirt. He was especially well-dressed today, and Sayu bleakly suspected it was because he had gone on a date. And with Misa, she imagined.

Light loosened his tie and undid the first button on his shirt to relax the collar a bit. He looked at her again. She immediately focused her attention on her own reflection in the mirror, realizing she had been staring at him just as long as he had stared at her. But how could she have helped it? The shirt more than reinforced his clean-cut good looks.

"Sayu, I'd like to talk to you."

She resisted the urge to close her eyes. A part of her had been expecting this.

"About what?" She continued combing even though her hair had long since been untangled.

"About you," was his simple reply. Sayu watched as Light took three long, measured steps so he was standing a few feet behind her. "You haven't been yourself lately."

She forced a smile onto her face. "I don't know what you're talking about, onii-chan," she remarked in an attempt to make light of their conversation. "I've just been busy with school like you have. It's just a little stress. Nothing else."

He fixed his gaze on her again. "Your friend stopped by earlier while you were taking a shower," he finally said. "I asked her what your class was learning in Algebra, and she said you were covering linear functions." Light held up her textbook.

"You've always had problems with graphing, Sayu. Why didn't you come to me for help like you used to?"

"Linear functions aren't so hard," she lied.

"She told me you were struggling with them even more than quadratic functions."

"I…I didn't want to bother you. Like you told me at the beginning of the week, you have midterms. And I knew you were studying, so…" she trailed off hesitantly.

"That hasn't stopped you before." He inserted a brief pause before continuing. "You haven't been joining us for dinner either. Dad was home for dinner yesterday, and you know that's rarity because he's always so busy with the Kira investigation. Why didn't you eat with the rest of us?"

"I wasn't hungry." Sayu was starting to feel like this was some sort of absurd interrogation.

"Listen." Light's voice softened a bit. "I'm your older brother. You know you can talk to me about anything."

_No, I can't. Not about this. _

"I realize we haven't spent as much time together as we used to since I entered college. But if there's something wrong with you, I want to know about it. I'm here for you. You should already know that."

"It's…it's nothing." Her voice was beginning to tremble and she struggled to hold herself together. The compassion in his usually stoic voice all but shattered what was left of her self-possession. "Don't worry about it, onii-chan."

"Tell me, Sayu. Why have you been avoiding mom and dad so much? Why have you…" He took a swift step forward and rolled her stool back, turning it so that she faced him.

"…been avoiding _me_?"

The only sound in the room was a small _tap_ as the comb made contact with the floor. She stared at him, eyes widened, face frozen. His face was inches from hers. She desperately wanted to look away but found that she couldn't. Not with his eyes burning into hers with this much intensity.

"Because I…"

It was more than she could take. He was too close to her, too close for comfort. And he was so very…

"Because you…?"

Sayu felt her face warm and shut her eyes tightly. She knew that she would regret saying this the moment it left her lips, but she couldn't keep it in any longer. He had to know.

"Because I _like_ you, onii-chan!"

Sayu opened her eyes just in time to see Light straighten and take a small backwards. His jaw was set and his hair fell over his eyes, completely masking them from her view. She swallowed, coming to the lackluster resolve that since she'd already started, she might as well continue.

_Matters can't possibly get any worse than they are by now, anyway. _

"I stopped coming in and asking for help because I wanted to avoid doing something that might make you suspect me. I wanted to avoid all this…" Her face felt hotter than before and tears stung her eyes. "I know it sounds stupid and horrible and wrong, but the truth is: I have a _crush on you_! And I've had one for the longest time!" Sayu trembled, wanting him to do something, anything. Even yelling or hitting was better than this taut silence. But he didn't move, didn't even look at her. He just stood there, as still and cold as a statue. She moved away from him towards the door, blinking back the tears that threatened to emerge from her eyes any second.

"I understand if you hate me. Gomennasai, onii-chan. I'm so sorry." _You're such an idiot, Sayu! You just ruined everything! Light will never think of you like the way he did before. Your brother-sister relationship is over! Nothing will ever be the same again!_

She grasped the doorknob with a shaking hand…

…only to have it pushed away by Light.

Sayu gasped as she was pulled away from the door. Light deftly locked the door with one fluid movement of his hand as his arm came to wrap around her waist. She stiffened at the feeling of his chest pressed firmly against her back.

"I don't hate you, Sayu." He drew his hand back from the door and spoke directly into her ear. "For the record, I'm glad you told me. That way I won't have to worry when I do this…" He slowly ran his hand down the length of her arm, stopping only when he reached her hand.

Her mouth was dry and she had to try multiple times before managing to get her voice to work. "But this…this is wrong…" She hesitated before adding, "…isn't it?"

Light turned her around in his arms so that she faced him. He promptly lowered his head and ran his lips across hers, pulling back slightly in order to whisper "Is it?" before fully kissing her.

Sayu felt her heart skip a beat as she tried to process what exactly was happening. Light—_her brother_—was actually kissing her, and in no way did he seem discouraged that she wasn't kissing him back.

Yet.

Slowly but surely she did respond to his kiss. She was tentative at first, unsure of how she should react, but in a matter of moments found herself lost in the sensation of their lips pressed together. Her hand came up to rest against the back of his neck as she pushed her lips upward, already wanting, craving, _needing_ more.

Light broke away from her so suddenly, so quickly that it left her disoriented. She watched as he made his way over to her vanity and took a seat on her stool. He leaned forward, elbows on knees, chin on interlocked fingers, staring at her with an unreadable expression.

Sayu tensed and looked down at her feet, wondering if her brother's unanticipated kiss had merely been a way for him to finalize what she had told him. If it had been some sort of a test, then she had passed with flying colors. She had kissed back with more than enough intensity to convince him that she had meant every word of what had been said.

Which could be a problem, considering. What if he hadn't counted on her reaction? What if that was the reason he had ended the kiss so abruptly?

As Sayu mentally debated her dilemma, she glanced up to see Light's lips curve into a sly smirk. And his smirk only broadened as he undid his tie and discarded it on the floor with a flick of his wrist.

He straightened and beckoned her forward with a finger. She took a reluctant step towards him.

"Onii-chan?"

Without warning, Light moved forward and clasped his hand around her wrist, tugging her towards him. The amount of force he used caused her to trip over his feet and collapse on top of him. He steadied her with his arm, shifting her slightly so that she was comfortably seated on his lap.

She stared at him speechlessly. He grinned back complacently.

"Just call me Light."

And then he kissed her again, except he didn't hold back like before. He used his entire mouth this time, lips parting, hands roaming feely over her back and shoulders. She kissed back just as deeply, coming to the sudden decision that something that felt so good, so _right_ couldn't possibly be so wrong.

Right?

But it didn't matter to her either way because it all felt so incredible; it was even better than the first time. Sayu straightened as his deft hands continued to move up and down her back rhythmically. She found her fingers in his hair seconds later, slowly running through the short auburn locks that she had wanted to touch for so long. It was like feathers brushing against her fingertips.

Light moved away from her mouth, giving Sayu a chance to finally get a breath of much-needed air. She licked her lips, realizing that Light tasted just as good as he smelled.

And looked, for that matter.

He planted a kiss on her neck, just below her left ear and close to her jaw. She gasped and titled her head back at the sensation.

"Onii…"—she caught herself at the last minute—"…_Light_."

Although Sayu didn't see his face, she could hear the smirk in his voice when he said "I'm glad you caught on," before resuming the task of trailing butterfly kisses down her neck. Her fingers tightened in his hair as his kisses went lower, his warm breath tickling the sensitive skin at her neck.

Sayu made a daring move and jerked away from him. Light shot her a frown of clear discontent and stared at her through a lock of hair with an expression that distinctly read "What was that for?"

Her response was a kiss, which Light readily agreed to. But she found herself so taken aback by her own audacity that she almost stopped kissing him…

…which was something Light adamantly refused to allow because he coaxed her back into the moment with his lips.

Though needless to say, she gladly let him.

His hand was pressed against the small of her back now while his fingers gently swept across the fabric of her pajama top. His other hand rested on the side of her waist, chasing a small shiver through her every time she thought about it.

It was all too perfect, really. Just as perfect as him. And as they continued to kiss, she couldn't help but wonder if anything could possibly ruin—

A knock.

"Light? Are you in there with Sayu?"

—the moment.

They broke apart simultaneously. Sayu look at her brother with a blank expression, but he was already staring at the door with an expression that could only be defined as disdain. As she finally comprehended what had happened, she stifled a gasp and instead buried her face at the hollow where Light's shoulder met his neck, trying to regain her composure and catch her breath at the same time.

Another knock.

"Light? Sayu? Are you—"

Light exhaled a deep breath that was easily passed off as a sigh of exasperation. "Hai, okaa-san, we're in here. I'm just helping Sayu with some homework."

Sayu was stunned at how casual and controlled Light's voice sounded, never mind how clever he had been to have the presence of mind of locking the door.

"All right. Well, dinner will be ready in a few minutes. Finish up and hurry downstairs." Their mother paused. "Sayu, will you be joining us tonight?"

She felt her brother give her a quick glance.

"I think I've convinced her to join us for dinner tonight," Light replied evenly.

"Ureshii wa!" She heard their mother clap her hands together outside the door. "That's good to hear!" Shuffling was heard as their mother walked away from the door and proceeded back downstairs.

Silence passed between them as Sayu came to the sudden realization that she'd had her first and perhaps most intense make-out session in her life with…her brother.

And she didn't regret it at all.

Light motioned that he wanted to stand and Sayu slid off his lap almost unwillingly. As she observed him smooth down the strands of his disheveled hair, she came to the conclusion that she should follow his lead and do the same thing. She could only imagine how tangled her hair was by now, not to mention how flushed her face probably was. Sayu put a hand to her cheek, finding it to be warm.

Light moved past her towards the door, his hand brushing against hers in the process. Whether it was intentional or unintentional, she didn't know, and for the moment, she didn't care. Her gaze was centered on his departing figure the entire time, her mind trying to deduce what exactly he could have been thinking.

Light looked over his shoulder at her. "I'll see you downstairs, Sayu." He grinned again, eyes flashing so unnaturally that Sayu could have swore they flickered from brown to scarlet.

The door was shut softly behind him and she was left alone to her thoughts. She absentmindedly swept a finger across her lips, still feeling the warm imprint of Light's lips against hers.

Sayu then felt herself do something that she hadn't been able to genuinely do in weeks.

She smiled.

* * *

Next week, when their mother questioned them both about why she had found Light's tie near her dressing table, Sayu would lie and say it had probably gotten mixed up with the laundry.

And Light would nod with an innocent smile before retorting with an offhand question of his own:

"Why else would it be there?"

* * *

_And I imagine Ryuk would be in the background laughing at this rather cracky predicament. _


End file.
